Process for polymerizing 1-hexene or higher alpha-olefins

ABSTRACT

A process for preparing a polymer containing derived units of one or more alpha olefins of formula CH 2 ═CHW wherein W is a C 3 -C 10  hydrocarbon radical and optionally from 0 to 81% by mol of derived units of propylene or 1-butene, comprising contacting under polymerization conditions one or more alpha olefins of formula CH 2 ═CHW and optionally propylene or  1 -butene in the presence of a catalyst system obtainable by contacting:
     a) a metallocene compound of formula (I)   

     
       
         
         
             
             
         
       
         
         
           
             wherein M, X, L, T 1 , T 2 , T 3  and R 1  are described in the text; and 
           
         
         (b) an alumoxane or a compound capable of forming an alkyl metallocene cation.

This application is the U.S. national phase of International ApplicationPCT/EP2005/002481, filed Mar. 8, 2005, claiming priority to EuropeanPatent Application 04101020.8 filed Mar. 12, 2004, and European PatentApplication 04104351.4 filed Sep. 9, 2004, and the benefit under 35U.S.C. 119(e) of U.S. Provisional Application No. 60/554,110, filed Mar.17, 2004 and U.S. Provisional Application No. 60/610,064 filed Sep. 15,2004; the disclosures of International Application PCT/EP2005/002481,European Patent Applications 04101020.8 and 04104351.4 and U.S.Provisional Application Nos. 60/554,110 and 60/610,064, each as filed,are incorporated herein by reference.

The present invention relates to a process for obtaining a polymercomprising 1-hexene or higher alpha-olefins derived units, by using aspecific class of metallocene compounds, that allows to obtain polymershaving high molecular weight in high yields.

Metallocene compounds are well known catalyst components for thepolymerization of alpha-olefins. However they are mainly used for the(co)polymerization of ethylene, propylene and 1-butene. Polymerizationof 1-hexene and higher alpha olefins by using metallocene catalystcomponents is discussed in some papers. For example U.S. Pat. No.6,566,544 discloses in table 10 the polymerization of 1-hexene by usingInd₂ZrMe₂ and bis(2-phenylindenyl)zirconium dimethyl. The molecularweight of the obtained polymers are quite low. In Macromol. Chem. Phys.200, 1208-1219 (1999), 1-hexene is polymerized in the presence ofiPr(CpFlu)ZrCl₂. The polymer has a syndiotactic structure and themolecular mass of the polymer obtained is close to 20000 gmol⁻¹. InJournal of Polymer Science: Part A: Polymer Chemistry, Vol 37, 283-292(1999) a series of metallocene compounds have been tested in 1-hexenepolymerization. Rac-[Me₂Ge(η⁵-C₅H-2,3,5-Me₃)MCl₂ (M=Zr or Hf) allows toobtain 1-hexene polymers having a very high molecular weight. Howeverthe drawback of this compound is that it is necessary to separate theracemic from the meso form, this makes the synthesis of such compoundmuch more difficult and expensive than the metallocene compound of thepresent invention. In the same article is also shown thatisopropyliden(9-fluorenyl)(cyclopentadienyl)zirconium dichlorideproduces 1-hexene polymer having very low molecular weight, with respectto the other compounds tested. The behaviour ofisopropyliden(9-fluorenyl)(cyclopentadienyl)zirconium dichloride isconfirmed in Macromol. Mater. Eng. 2001, 286, 480-487. In this paper themolecular weight (Mw) of 1-hexene polymer obtained by using saidcompound is about 45000.

WO 01/46278 relates to a polymerization process for producing acopolymer containing from 60 to 94% mol of alpha olefins having from 3to 6 carbon atoms, and from 6 to 40% mol of alpha olefins having atleast one carbon atom more than the first one. In the examples propyleneis copolymerized with 1-hexene. These copolymers are obtained with ametallocene compound different from that one used in the presentinvention, moreover the molecular weight of the obtained copolymers canstill be improved. Finally the present invention is directed to acopolymer that contains a smaller amount of propylene or 1-butene.

In Macromol. Chem. Phys. 197, 563-573 (1996) are described a series ofhexene propylene copolymers having various content of comonomer from 0to 100% by mol. The copolymers are obtained by using Et(Ind)₂HfCl₂ andboth the yields and the molecular weight of the obtained polymers can befurther improved.

Thus there is still the need to find a class of metallocene compoundseasy to prepare and without the drawback to separate the racemic fromthe meso form able to give 1-hexene or higher alpha-olefins (co)polymershaving an high molecular weight in high yields.

An object of the present invention is a process for preparing a polymercontaining derived units of one or more alpha olefins of formula CH₂═CHWwherein W is a C₃-C₁₀ hydrocarbon radical and optionally from 0 to 81%by mol; preferably from 0 to 70% by mol, more preferably from 0 to 59%by mol, of derived units of propylene or 1-butene, comprising contactingunder polymerization conditions one or more alpha olefins of formulaCH₂═CHW and optionally propylene or 1-butene in the presence of acatalyst system obtainable by contacting:

-   a) a metallocene compound of formula (I)

-   -   wherein:    -   M is an atom of a transition metal selected from those belonging        to group 3, 4, or to the lanthanide or actinide groups in the        Periodic Table of the Elements; preferably M is zirconium        titanium or hafnium;    -   X, same or different, is a hydrogen atom, a halogen atom, or a        R, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ group, wherein R is a are        linear or branched, cyclic or acyclic, C₁-C₄₀-alkyl, C₂-C₄₀        alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl, C₇-C₄₀-alkylaryl or        C₇-C₄₀-arylalkyl radicals; optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;        or two X can optionally form a substituted or unsubstituted        butadienyl radical or a OR′O group wherein R′ is a divalent        radical selected from C₁-C₄₀ alkylidene, C₆-C₄₀ arylidene,        C₇-C₄₀ alkylarylidene and C₇-C₄₀ arylalkylidene radicals;        preferably X is a hydrogen atom, a halogen atom or a R group;        more preferably X is chlorine or a C₁-C₁₀-alkyl radical; such as        methyl, or ethyl radicals;    -   L is a divalent C₁-C₄₀ hydrocarbon radical optionally containing        heteroatoms belonging to groups 13-17 of the Periodic Table of        the Elements or a divalent silylene radical containing up to 5        silicon atom; preferably L is a divalent bridging group selected        from C₁-C₄₀ alkylidene, C₃-C₄₀ cycloalkylidene, C₆-C₄₀        arylidene, C₇-C₄₀ alkylarylidene, or C₇-C₄₀ arylalkylidene        radicals optionally containing heteroatoms belonging to groups        13-17 of the Periodic Table of the Elements, and silylene        radical containing up to 5 silicon atoms such as SiMe₂, SiPh₂;        preferably L is a group (Z(R″)₂)_(r) wherein Z is a carbon or a        silicon atom, n is 1 or 2 and R″ is a C₁-C₂₀ hydrocarbon radical        optionally containing heteroatoms belonging to groups 13-17 of        the Periodic Table of the Elements; preferably R″ is a linear or        branched, cyclic or acyclic, C₁-C₂₀-alkyl, C₂-C₂₀ alkenyl,        C₂-C₂₀ alkynyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or        C₇-C₂₀-arylalkyl radicals optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;        more preferably the group (Z(R″)₂)_(n) is Si(CH₃)₂, SiPh₂,        SiPhMe, SiMe(SiMe₃), CH₂, (CH₂)₂, and C(CH₃)₂;    -   R¹, is a hydrogen atom, or a C₁-C₄₀ hydrocarbon radicals        optionally containing heteroatoms belonging to groups 13-17 of        the Periodic Table of the Elements; Preferably R¹ is a hydrogen        atom or a linear or branched, cyclic or acyclic, C₁-C₄₀-alkyl,        C₂-C₄₀ alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl, C₇-C₄₀-alkylaryl or        C₇-C₄₀-arylalkyl radicals; optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;        more preferably R¹ is linear or branched, saturated or        unsaturated C₁-C₂₀-alkyl radicals, optionally containing        heteroatoms belonging to groups 13-17 of the Periodic Table of        the Elements; even more preferably R¹ is a C₁-C₁₀-alkyl radical        such as a methyl, or ethyl radical;    -   T¹ is a moiety of formula (IIa) or (IIb):

-   -   wherein the atom marked with the symbol * bonds the atom marked        with the same symbol in the compound of formula (I);    -   R², R³, R⁴ and R⁵, equal to or different from each other, are        hydrogen atoms, or C₁-C₄₀ hydrocarbon radicals optionally        containing heteroatoms belonging to groups 13-17 of the Periodic        Table of the Elements; or two adjacent R², R³, R⁴ and R⁵ can        optionally form a saturated or unsaturated, 5 or 6 membered        rings, said ring can bear C₁-C₂₀ alkyl radicals as substituents;        Preferably R², R³, R⁴ and R⁵ are hydrogen atoms or linear or        branched, cyclic or acyclic, C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl,        C₂-C₄₀ alkynyl, C₆-C₄₀-aryl, C₇-C₄₀-alkylaryl or        C₇-C₄₀-arylalkyl radicals; optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;    -   R² is preferably a linear or branched, saturated or unsaturated        C₁-C₂₀-alkyl radical, optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;        preferably R² is a C₁-C₁₀-alkyl radical; more preferably R² is a        methyl, ethyl or isopropyl radical;    -   R⁴ is preferably a hydrogen atom or a C₁-C₁₀-alkyl radical such        as a methyl, ethyl or isopropyl radical;    -   R⁵ is preferably a hydrogen atom or linear or branched,        saturated or unsaturated C₁-C₂₀-alkyl radical, optionally        containing heteroatoms belonging to groups 13-17 of the Periodic        Table of the Elements; preferably a C₁-C₁₀-alkyl radical; more        preferably R⁵ is a methyl or ethyl radical;    -   R⁶ and R⁷, equal to or different from each other, are hydrogen        atoms or C₁-C₄₀ hydrocarbon radicals optionally containing        heteroatoms belonging to groups 13-17 of the Periodic Table of        the Elements; or R⁶ and R⁷ can optionally form a saturated or        unsaturated, 5 or 6 membered rings, said ring can bear C₁-C₂₀        alkyl radicals as substituents; preferably R⁶ and R⁷ are        hydrogen atoms or linear or branched, cyclic or acyclic,        C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl,        C₇-C₄₀-alkylaryl or C₇-C₄₀-arylalkyl radicals; optionally        containing heteroatoms belonging to groups 13-17 of the Periodic        Table of the Elements;    -   preferably R⁷ is a hydrogen atom or a linear or branched, cyclic        or acyclic C₁-C₂₀-alkyl radical; more preferably R⁷ is a methyl        or ethyl radical; preferably R⁶ is a C₁-C₄₀-alkyl, C₆-C₄₀-aryl        or a C₇-C₄₀-arylalkyl; more preferably R⁶ is a group of formula        (III)

-   -   wherein R⁸, R⁹, R¹⁰, R¹¹ and R¹², equal to or different from        each other, are hydrogen atoms or C₁-C₂₀ hydrocarbon radicals;        preferably R⁸, R⁹, R¹⁰, R¹¹ and R¹² are hydrogen atoms or linear        or branched, cyclic or acyclic, C₁-C₂₀-alkyl, C₂-C₂₀ alkenyl,        C₂-C₂₀ alkynyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or        C₇-C₂₀-arylalkyl radicals; preferably R⁸, and R¹¹ are a hydrogen        atoms; R⁹, R¹⁰ and R¹² are preferably hydrogen atoms or linear        or branched, cyclic or acyclic, C₁-C₁₀-alkyl radicals;    -   T², equal to or different from each other, are moieties of        formula (IIc) or (IId):

-   -   wherein the atom marked with the symbol * bonds the atom marked        with the same symbol in the compound of formula (I);    -   R¹³, equal to or different from each other, are hydrogen atoms        or C₁-C₄₀ hydrocarbon radicals optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;        or two R¹³ can optionally form a saturated or unsaturated, 5 or        6 membered rings, said ring can bear C₁-C₂₀ alkyl radicals as        substituents; preferably R¹³ are hydrogen atoms or linear or        branched, cyclic or acyclic, C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl,        C₂-C₄₀ alkynyl, C₆-C₄₀-aryl, C₇-C₄₀-alkylaryl or        C₇-C₄₀-arylalkyl radicals; optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;        more preferably R¹³ are a hydrogen atoms or linear or branched,        C₁-C₂₀-alkyl radicals;    -   R¹⁴, equal to or different from each other, are hydrogen atoms        or C₁-C₄₀ hydrocarbon radicals optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;        preferably R¹⁴ are linear or branched, cyclic or acyclic,        C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl,        C₇-C₄₀-alkylaryl or C₇-C₄₀-arylalkyl radicals; optionally        containing heteroatoms belonging to groups 13-17 of the Periodic        Table of the Elements; more preferably R¹⁴ are linear or        branched, C₁-C₂₀-alkyl radicals;

-   (b) an alumoxane or a compound capable of forming an alkyl    metallocene cation; and optionally

-   (c) an organo aluminum compound.

In one embodiment the compound of formula (I) has the following formula(IV)

wherein M, X, L, R¹, R⁶, R⁷, and R¹⁴ are described above.

In a further alternative embodiment the compound of formula (I) has thefollowing formula (V)

wherein M, X, L, R¹, R², R⁵ and R¹⁴ are described above.compounds of formula (I) are well know in the art, they can be preparedfor example as described in WO 01/47939 or EP 707 016.

Alumoxanes used as component b) can be obtained by reacting water withan organo-aluminium compound of formula H_(j)AlU_(3-j) orH_(j)Al₂U_(6-j), where the U substituents, same or different, arehydrogen atoms, halogen atoms, C₁-C₂₀-alkyl, C₃-C₂₀-cyclalkyl,C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl radicals, optionallycontaining silicon or germanium atoms, with the proviso that at leastone U is different from halogen, and j ranges from 0 to 1, being also anon-integer number. In this reaction the molar ratio of Al/water ispreferably comprised between 1:1 and 100:1.

Alumoxanes used as component b) can be obtained by reacting water withan organo-aluminium compound of formula H_(j)AlU_(3-j) orH_(j)Al₂U_(6-j), where the U substituents, same or different, arehydrogen atoms, halogen atoms, C₁-C₂₀-allyl, C₃-C₂₀-cyclalkyl,C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl radicals, optionallycontaining silicon or germanium atoms, with the proviso that at leastone U is different from halogen, and j ranges from 0 to 1, being also anon-integer number. In this reaction the molar ratio of Al/water ispreferably comprised between 1:1 and 100:1.

The alumoxanes used in the process according to the invention areconsidered to be linear, branched or cyclic compounds containing atleast one group of the type:

wherein the substituents U, same or different, are defined above.

In particular, alumoxanes of the formula:

can be used in the case of linear compounds, wherein n¹ is 0 or aninteger of from 1 to 40 and the substituents U are defined as above; oralumoxanes of the formula:

can be used in the case of cyclic compounds, wherein n² is an integerfrom 2 to 40 and the U substituents are defined as above.

Examples of alumoxanes suitable for use according to the presentinvention are methylalumoxane (MAO), tetra-(isobutyl)alumoxane (TIBAO),tetra-(2,4,4-trimethyl-pentyl)alumoxane (TIOAO),tetra-(2,3-dimethylbutyl)alumoxane (TDMBAO) andtetra-(2,3,3-trimethylbutyl)alumoxane (TTMBAO).

Particularly interesting cocatalysts are those described in WO 99/21899and in WO01/21674 in which the alkyl and aryl groups have specificbranched patterns.

Non-limiting examples of aluminium compounds that can be reacted withwater to give suitable alumoxanes (b), described in WO 99/21899 andWO01/21674, are: tris(2,3,3-trimethyl-butyl)aluminium,tris(2,3-dimethyl-hexyl)aluminium, tris(2,3-dimethyl-butyl)aluminium,tris(2,3-dimethyl-pentyl)aluminium, tris(2,3-dimethyl-heptyl)aluminium,tris(2-methyl-3-ethyl-pentyl)aluminium,tris(2-methyl-3-ethyl-hexyl)aluminium,tris(2-methyl-3-ethyl-heptyl)aluminium,tris(2-methyl-3-propyl-hexyl)aluminium,tris(2-ethyl-3-methyl-butyl)aluminium,tris(2-ethyl-3-methyl-pentyl)aluminium,tris(2,3-diethyl-pentyl)aluminium,tris(2-propyl-3-methyl-butyl)aluminium,tris(2-isopropyl-3-methyl-butyl)aluminium,tris(2-isobutyl-3-methyl-pentyl)aluminium,tris(2,3,3-trimethyl-pentyl)aluminium,tris(2,3,3-trimethyl-hexyl)aluminium,tris(2-ethyl-3,3-dimethyl-butyl)aluminium,tris(2-ethyl-3,3-dimethyl-pentyl)aluminium,tris(2-isopropyl-3,3-dimethyl-butyl)aluminium,tris(2-trimethylsilyl-propyl)aluminium,tris(2-methyl-3-phenyl-butyl)aluminium,tris(2-ethyl-3-phenyl-butyl)aluminium,tris(2,3-dimethyl-3-phenyl-butyl)aluminium,tris(2-phenyl-propyl)aluminium,tris[2-(4-fluoro-phenyl)-propyl]aluminium,tris[2-(4-chloro-phenyl)-propyl]aluminium,tris[2-(3-isopropyl-phenyl)-propyl]aluminium,tris(2-phenyl-butyl)aluminium, tris(3-methyl-2-phenyl-butyl)aluminium,tris(2-phenyl-pentyl)aluminium,tris[2-(pentafluorophenyl)-propyl]aluminium,tris[2,2-diphenyl-ethyl]aluminium andtris[2-phenyl-2-methyl-propyl]aluminium, as well as the correspondingcompounds wherein one of the hydrocarbyl groups is replaced with ahydrogen atom, and those wherein one or two of the hydrocarbyl groupsare replaced with an isobutyl group.

Amongst the above aluminium compounds, trimethylaluminium (TMA),triisobutylaluminium (TTBA), tris(2,4,4-trimethyl-pentyl)aluminium(TIOA), tris(2,3-dimethylbutyl)aluminium (TDMBA) andtris(2,3,3-trimethylbutyl)aluminium (TTMBA) are preferred.

Non-limiting examples of compounds able to form an alkylmetallocenecation are compounds of formula D⁺E⁻, wherein D⁺ is a Brønsted acid,able to donate a proton and to react irreversibly with a substituent Xof the metallocene of formula (I) and E⁻ is a compatible anion, which isable to stabilize the active catalytic species originating from thereaction of the two compounds, and which is sufficiently labile to beremoved by an olefinic monomer. Preferably, the anion E⁻ comprises oneor more boron atoms. More preferably, the anion E⁻ is an anion of theformula BAr₄ ⁽⁻⁾, wherein the substituents Ar which can be identical ordifferent are aryl radicals such as phenyl, pentafluorophenyl orbis(trifluoromethyl)phenyl. Tetrakis-pentafluorophenyl borate isparticularly preferred compound, as described in WO 91/02012. Moreover,compounds of formula BAr₃ can be conveniently used. Compounds of thistype are described, for example, in the International patent applicationWO 92/00333. Other examples of compounds able to form analkylmetallocene cation are compounds of formula BAr₃P wherein P is asubstituted or unsubstituted pyrrol radical. These compounds aredescribed in WO01/62764. Compounds containing boron atoms can beconveniently supported according to the description of DE-A-19962814 andDE-A-19962910. All these compounds containing boron atoms can be used ina molar ratio between boron and the metal of the metallocene comprisedbetween about 1:1 and about 10:1; preferably 1:1 and 2.1; morepreferably about 1:1.

Non limiting examples of compounds of formula D⁺E⁻ are:

-   Triethylammoniumtetra(phenyl)borate,-   Tributylammoniumtetra(phenyl)borate,-   Trimethylammoniumtetra(tolyl)borate,-   Tributylammoniumtetra(tolyl)borate,-   Tributylammoniumtetra(pentafluorophenyl)borate,-   Tributylammoniumtetra(pentafluorophenyl)aluminate,-   Tripropylammoniumtetra(dimethylphenyl)borate,-   Tributylammoniumtetra(trifluoromethylphenyl)borate,-   Tributylammoniumtetra(4-fluorophenyl)borate,-   N,N-Dimethylbenzylammonium-tetrakispentafluorophenylborate,-   N,N-Dimethylhexylamonium-tetrakispentafluorophenylborate,-   N,N-Dimethylaniliniumtetra(phenyl)borate,-   N,N-Diethylaniliniumtetra(phenyl)borate,-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)borate,-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)aluminate,-   N,N-Dimethylbenzylammonium-tetrakispentafluorophenylborate,-   N,N-Dimethylhexylamonium-tetrakispentafluorophenylborate,-   Di(propyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Di(cyclohexyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Triphenylphosphoniumtetrakis(phenyl)borate,-   Triethylphosphoniumtetrakis(phenyl)borate,-   Diphenylphosphoniumtetrakis(phenyl)borate,-   Tri(methylphenyl)phosphoniumtetrakis(phenyl)borate,-   Tri(dimethylphenyl)phosphoniumtetrakis(phenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)aluminate,-   Triphenylcarbeniumtetrakis(phenyl)aluminate,-   Ferroceniumtetrakis(pentafluorophenyl)borate,-   Ferroceniumtetrakis(pentafluorophenyl)aluminate.-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate, and-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)borate.

Organic aluminum compounds used as compound iii) are those of formulaH_(j)AlU_(3-j) or H_(j)Al₂U_(6-j) as described above.

The polymerization process of the present invention can be carried outin liquid phase, optionally in the presence of an inert hydrocarbonsolvent. Said hydrocarbon solvent can be either aromatic (such astoluene) or aliphatic (such as propane, hexane, heptane, isobutane,cyclohexane and 2,2,4-trimethylpentane). Preferably, the polymerizationprocess of the present invention is carried out by using the alphaolefin of formula CH₂═CHW wherein W is a C₃-C₁₀ hydrocarbon radical suchas 1-hexene or 1-octene as polymerization medium, i.e. the same olefinthat is going to be polymerizated for example 1-hexene is used aspolymerization medium when a 1-hexene-based polymer is the wishedpolymer.

The polymerization temperature preferably ranges from 0° C. to 250° C.;more preferably it is comprised between 20° C. and 150° C. and, moreparticularly the polymerization temperature is between 40° C. and 90°C.;

The molecular weight distribution can be varied by using mixtures ofdifferent metallocene compounds or by carrying out the polymerization inseveral stages which differ as to the polymerization temperature and/orthe concentrations of the molecular weight regulators and/or themonomers concentration. Moreover by carrying out the polymerizationprocess by using a combination of two different metallocene compounds offormula (I) a polymer endowed with a broad melting is produced.

With the process of the present invention isotactic polymers endowedwith high molecular weights can be obtained in high yields.

With the process of the present invention polymers containing derivedunits of one or more alpha olefins of formula CH₂═CHW wherein W is aC₃-C₁₀ hydrocarbon radical and optionally from 0 to 81% by mol ofderived units of propylene or 1-butene can be obtained. Examples ofalpha olefins of formula CH₂═CHW are 1-pentene; 1-hexene; 1-octene and1-decene. Preferably 1-hexene and 1-octene are used; more preferably1-hexene is used.

When said alpha olefins of formula CH₂═CHW are copolymerized withpropylene or 1-butene preferably the obtained copolymer has a content ofderived units of propylene or 1-butene ranging from 0.1% by mol to 59%by mol; more preferably the content of propylene or 1-butene ranges from10% by mol to 50% by mol, even more preferably it ranges from 19% by molto 40% by mol.

The obtained copolymer is endowed with the following properties:

-   i) intrinsic viscosity IV measured in tetrahydronaphtalene (THN) at    135° C. higher than 0.90 dl/g; preferably higher than 1.20 dl/g;    more preferably higher than 1.30 dl/g; even more preferably higher    than 1.80 dl/g;-   ii) distribution of molecular weight Mw/Mn lower than 3; preferably    lower than 2.5; and-   iii) no enthalpy of fusion detectable at a differential scanning    calorimeter (DSC) wherein the DSC measurement is carried out as    described below.

Preferably in said copolymers the alpha olefin of formula CH₂═CHW is1-hexene or 1-octene.

The copolymers, other than the above properties, are further endowedwith a very low Shore A (measured according to ISO 868), in particularthe shore A is lower than 30; preferably lower than 25; more preferablylower than 20; and furthermore the tensile modulus is lower than 20 MPa(measured according to ASTM 5026,4092 e 4065); preferably lower than 15MPa; more preferably lower than 11 MPa.

A further preferred range of content of derived units of propylene and1-butene is from 19% by mol to 59% by mol; even more preferably from 30%by mol to 59% by mol.

The process of the present invention is particularly suitable forpreparing homopolymers of alpha olefins of formula CH₂═CHW wherein W isa C₃-C₁₀ hydrocarbon radical, in particular homopolymers of 1-hexene or1-octene; preferably homopolymer of 1-hexene are produced.

The homopolymer prepared according to the present invention can be usedfor application known in the art such as masterbatches or in adhesiveformulations.

Even if the homopolymer of the present invention are not exemplified,their preparation can be easily achieved by the skilled man once it isknow the process for preparing the copolymers. In fact it is sufficientto avoid to add the comonomer in the processes exemplified above forobtaining the wished homopolymer.

The copolymers obtainable with the process of the present inventiondescribed above, can have the same uses of the homopolymer andfurthermore they can be used as compatibilizer. For example they canimprove the dispersion of a rubber phase in an crystalline matrix, dueto the presence of the comonomer that help to compatibilize the twophases, so that a material having an improved izod impact value con beobtained.

The following examples are given to illustrate and not to limit theinvention.

EXAMPLES General Procedures and Characterizations

All chemicals were handled under nitrogen using standard Schlenktechniques. Methylalumoxane (MAO) was received from Albemarle as a 30%wt/vol toluene solution and used as such.

Pure triisobutylaluminum (TIBA) was used as such.

Isododecane was purified over aluminum oxide to reach a water contentbelow 10 ppm.

A 101 g/L TIBA/isododecane solution was obtained by mixing the abovecomponents.

The melting points of the polymers (T_(m)) were measured by DifferentialScanning Calorimetry (D.S.C.) on a Perkin Elmer DSC-7 instrument,according to the standard method. A weighted sample (5-7 mg) obtainedfrom the polymerization was sealed into aluminum pans and heated to 180°C. at 10° C./minute. The sample was kept at 180° C. for 5 minutes toallow a complete melting of all the crystallites, then cooled to 20° C.at 10° C./minute. After standing 2 minutes at 20° C., the sample washeated for the second time to 180° C. at 10° C./min. In this secondheating run, the peak temperature was taken as the melting temperature(T_(m)) and the area of the peak as melting enthalpy (ΔH_(f)).

Molecular weight parameters were measured using a Waters 150C ALC/GPCinstrument (Waters, Milford, Mass., USA) equipped with four mixed-gelcolumns PLgel 20 μm Mixed-A LS (Polymer Laboratories, Church Stretton,United Kingdom). The dimensions of the columns were 300×7.8 mm. Thesolvent used was TCB and the flow rate was kept at 1.0 mL/min. Solutionconcentrations were 0.1 g/dL in 1,2,4 trichlorobenzene (TCB). 0.1 g/L of2,6-di-t-butyl-4-methyl phenol (BHT) was added to prevent degradationand the injection volume was 300 μL. All the measurements were carriedout at 135° C. GPC calibration is complex, as no well-characterizednarrow molecular weight distribution standard reference materials areavailable for 1-hexene polymers. Thus, a universal calibration curve wasobtained using 12 polystyrene standard samples with molecular weightsranging from 580 to 13,200,000. It was assumed that the K values of theMark-Houwink relationship were: K_(PS)=1.21×10⁻⁴, dL/g andK_(PH)=1.78×10⁻⁴ dL/g for polystyrene and poly-1-hexene respectively,for the copolymers the same K_(PH) has been used. The Mark-Houwinkexponents a were assumed to be 0.706 for polystyrene and 0.725 forpoly-1-hexene and copolymers. Even though, in this approach, themolecular parameters obtained were only an estimate of the hydrodynamicvolume of each chain, they allowed a relative comparison to be made.

The intrinsic viscosity (I.V.) was measured in tetrahydronaphtalene(THN) at 135° C. Racdimethylsilyl{(2,4,7-trimethyl-1-indenyl)-7-(2,5-dimethyl-cyclopenta[1,2-b:4,3-b′]-dithiophene)}zirconiumdimethyl (A-1) was prepared according to the following procedure: theligand,[3-(2,4,7-trimethylindenyl)][7-(2,5-dimethyl-cyclopenta[1,2-b:4,3-b′]-dithiophene)]dimethylsilane, was prepared as described in WO 01/47939. 30.40 g of this ligand(72.26 mmol) and 170 ml of anhydrous THF were charged under nitrogen ina cylindrical glass reactor equipped with magnetic stirring bar. Thebrown solution so obtained was cooled and maintained at 0° C., while58.4 ml of n-BuLi 2.5M in hexane (146 mmol) were added dropwise viadropping funnel. At the end of the addition, the dark brown solution wasstirred for 1 hour at room temperature, then cooled to −50° C., and then48.6 ml of MeLi 3.05 M in diethoxymethane (148.2 mmol) were added to it.In a Schlenk, 16.84 g of ZrCl₄ (72.26 mmol) were slurried in 170 ml oftoluene. Both mixtures were kept at −50° C. and the ZrCl₄ slurry wasquickly added to the ligand dianion solution. At the end of theaddition, the reaction mixture was allowed to reach room temperature andstirred for an additional hour. A yellow-green suspension was obtained.¹H NMR analysis shows complete conversion to the target complex. Allvolatiles were removed under reduced pressure, and the obtained freeflowing brown powder was suspended in 100 ml of Et₂O. After stirring fora few minutes, the suspension was filtered over a G4 frit. The solid onthe frit was then washed twice with Et₂O (until the washing solventturns from brown to yellow), then dried under vacuum, and finallyextracted on the frit with warm toluene (60° C.), until the filteringsolution turns from yellow to colorless (about 650 ml of toluene); Theextract was dried under reduced pressure to give 28.6 g of yellowpowder, which ¹H-NMR showed to be the target complex, free fromimpurities. The yield based on the ligand was 73.3%.

¹H-NMR: (CD₂Cl₂, r.t.), ppm: −2.09 (s, 3H), −0.79 (s, 3H), 1.01 (s, 3H),1.04 (s, 3H), 2.38 (s, 3H), 2.39 (s, 3H), 2.43 (d, 3H, J=1.37 Hz), 2.52(s, 3H), 2.57 (d, 3H, J=1.37 Hz), 6.61 (dq, 1H, J=7.04 Hz, J=0.78 Hz),6.81 (q, 1H, J=1.37 Hz), 6.85 (dq, 1H, J=7.04 Hz, J=0.78 Hz), 6.87 (q,1H, J=1.37 Hz), 6.91 (s, 1H).

Flexural modulus, stress at break and elongation at break have beenmeasured according to ISO 527-1 and ISO 178, Stress at yield andelongation at yield have been measured according to ASTM D 638, tensilemodulus has been measured according to ASTM D 790, melt flow rate underthe condition 230° C./2.16 kg is measured according to ISO 1133. Izodhas been measured according to ASTM D256.

Preparation of Catalyst Systems

Preparation of Catalyst System C-1

9.7 cc of TIBA/isododecane solution were mixed with 1.9 cc of 30%MAO/toluene solution (MAO/TIBA, molar ratio 2:1). Then, 20 mg of A-1were dissolved with this solution. The metallocene was completelysoluble, the dark violet solution did not show any trace of residualsolid. The final solution was obtained upon recovery of 2.0 cc bydistillation. MAO/TIBA 2:1 mol/mol; Al_(tot)/Zr=400. This solution wasused to perform 1-hexene polymerization.

Polymerization Tests

1-hexene Homopolymerization, General Procedure.

To 20 g of liquid 1-hexene an amount of the catalyst solution obtainedas reported above containing 0.5 mg of metallocene, is added at 50° C.After 30 minutes, the polymerization is stopped with ethanol. Then,acetone is added to separate the polymer. Finally, the polymer is driedat 50° C. under vacuum for several hours. The results of the 1-hexenepolymerization tests are reported in Table 1.

TABLE 1 1-hexene polymerization results. Ex Cat. Ageing, days Yield, gActivity Kg/g_(met)h 1 C-1 1 13.46 53.8Preparation of Catalyst System C-2 A1/MAO:TIBA 2:1 (400)

33.3 ml of TIBA/isododecane solution (101 g/L) was mixed with 7.9 cc ofMAO/toluene solution (Albemarle −30% wt) to obtain a MAO/TIBA molarratio of 2:1. The solution was stirred for 1 hour at room temperature.Then, 69 mg of A-1 was dissolved in the solution.

The dark violet solution did not show any trace of residual solid.

The final solution was diluted with 13 ml of isododecane to reach aconcentration of 100 g/L.

1-hexene Copolymerisation

An amount of liquid 1-hexene as indicated in table 2 were fed in a 250ml glass vessel reactor at room temperature. The reactor had beenmaintained under slight positive nitrogen atmosphere. Consequently thetemperature was increased to the polymerization temperature indicated intable 2. An over pressure of 1 bar-g of propylene or 1-butene was fed inthe autoclave. The catalyst solution, (ageing indicated in table 2), wastransferred into the liquid, under a nitrogen flow. The pressure wasincreased with propylene until reaching the polymerisation pressureindicated in table 2. The polymerization was conducted for 60 minutes,then it was stopped by venting the monomers and the polymer wasprecipitated by adding acetone to the polymer solution. The recoveredpolymer was dried at 50° C. under vacuum. Polymerization and polymerdata are reported in table 2.

TABLE 2 Activity Cat 1-hexene Monomer Pol. Temp. Ageing Kg/g 1-hexene IVEx (mg. of A-1) g (bar-g) ° C. hours met/h mol % Mw Mw/Mn (THN) dl/g ΔH2 C-2 (0.38) 67 propylene (3) 50 1 11 76.5 n.a. n.a. 2.46 n.d. 3 C-2(0.38) 67 propylene (6) 50 4 32 58.5 n.a. n.a. 2.53 n.d. 4 C-2 (0.31) 401-butene (2) 50 450 30 53.1 396371 2.2 3.20 n.d.. 5 C-2 (0.31) 401-butene (2) 70 450 43 80.8 285718 1.9 1.33 n.d.. n.a. not availablen.d. not detectable

1-hexene/propylene or 1-butene copolymerisation

4 mmol of Al(i-Bu)₃ (as a 1M solution in hexane) and 1000 g of 1-hexenewere charged at room temperature in a 4-L jacketed stainless-steelautoclave, previously purified by washing with an Al(i-Bu)₃ solution inhexane and dried at 50° C. in a stream of nitrogen. The autoclave wasthen thermostated at the polymerisation temperature, 70° C., and thenthe solution containing the catalyst/cocatalyst solution indicated intable 3 aged as indicated in table 3 was injected in the autoclave bymeans of nitrogen pressure through the stainless-steel vial. The monomerwas fed until a pressure indicated in table 3 and the polymerisationcarried out at constant temperature for 1 hour. The polymerizationsolution was discharged into a heated steel tank containing water at 70°C. The tank heating was switched off and a flow of nitrogen at 0.5 bar-gwas fed. After cooling at room temperature, the steel tank was openedand the wet polymer collected and dried at 70° C. under reducedpressure. The polymerisation conditions and the characterisation data ofthe obtained polymers are reported in Table 3.

TABLE 3 Cat Monomer Activity 1-hexene IV Ex (mg. of A-1) (bar-g) Kg/gmet/h mol % Mw Mw/Mn (THN) dl/g ΔH 6 C-2 (2.58) propylene (20) 83 43232200 1.9 1.4 n.d. 7 C-2 (1.28) propylene (19) 117 20.7 229100 2.0 1.51n.a. 8 C-2 (2.56) 1-butene (5) 20 41 217200 2.3 1.25 n.d. 9 C-2 (2.6)Propylene (22) 148 46 217433 1.9 1.27 n.d.

The shore A (ISO 868) of copolymer of examples 6 and 8 has beenmeasured, the results are reported in table 4. The tensile modulus of asample of copolymers obtained in examples 6 and 8 has been measuredaccording to (ASTM 5026,4092 e 4065) as follows: Specimens for tensiletest are cut from compression moulding plaques. Specimen sizes areapprox. 40 mm long overall, 20 mm inter-clamp length, 6 mm width andthickness was 1 mm. Specimen is clamped in the SEIKO DMS 6100 tensileDMTA.

The applied frequency is 1 Hz.

Specimens are heated from −80° C. to +140° C. with 2° C./min as heatingrate; specimens are re-clamped at the low temperature.

The results are reported in table 4

TABLE 4 Ex shore A tensile modulus (MPa) 6 19 <10 8 7 <10Blends

Samples of copolymers obtained in examples 6, 7 and 9 have been blendedwith Moplen^((T))HP500N a propylene homopolymer sold by Basell. threeblends have been obtained by mixing in an extruder 20% of the copolymersof examples 6, 7 and 8 and 80% of Moplen HP500N. The blends marked as BA(copolymer of example 6); BB (copolymer of example 7) and BC (copolymerof example) have been analyzed in order to evaluate the mechanicalproperties, the results are reported in table 5

TABLE 5 Blend BC BA BB HP500N Melt flow rate g/10 min 13.1 13.1 14.3 1.8Tensile modulus MPa 1275 1130 1060 1450 (DMTA) 23° C. Stress at yieldN/MM2 24.8 23.7 21.5 33 Elongation at % 12.3 13 13.5 n.a. yield Stressat break N/MM2 16.6 15.4 12.6 n.a. Elongation at % 70 65 60 n.a. breakIZOD at 23° C. J/M 62.9 57.6 55 n.a. IZOD at −20° C. J/M 17 18.5 17 n.a.n.a. not available

It can be seen that the blend are much more softer than the homopolymeralone in fact, for example in the blend the tensile modulus isconsiderably lowered with respect to the homopolymer alone.

A blend of 8% of the copolymer obtained in example 6 and 82% ofHifax^((T)) 7378 heterophasic blend comprising a crystalline matrix anda rubber phase sold by Basell has been obtained n a brandbury mixer. Theresulting blend (BD) was analysed, the data are reported in table 6

TABLE 6 Blend BD Hifax 7378 Flexural modulus MPa 1030 705 IZOD at 23° C.J/M 11.3 11.9 IZOD at −20° C. J/M 6.6 5.8

1. A process for preparing a polymer containing derived units of1-hexene and 10% to 50% by mol of derived units of propylene or1-butene, and having an intrinsic viscosity of higher than 1.8 dl/g, theprocess comprising contacting under polymerization conditions hexene andpropylene or 1-butene in the presence of a catalyst system obtained bycontacting: a) a metallocene compound of formula (V):

wherein: M is an atom of a transition metal selected from thosebelonging to group 3, 4, or to the lanthanide or actinide groups in thePeriodic Table of the Elements; X, same or different, is a hydrogenatom, a halogen atom, or a R, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ group,wherein R is a are linear or branched, cyclic or acyclic, C₁-C₄₀-alkyl,C₂-C₄₀ alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl, C₇-C₄₀-alkylaryl orC₇-C₄₀-arylalkyl radicals; optionally containing heteroatoms belongingto groups 13-17 of the Periodic Table of the Elements; or two X canoptionally form a substituted or unsubstituted butadienyl radical or aOR′O group wherein R′ is a divalent radical selected from C₁-C₄₀alkylidene, C₆-C₄₀ arylidene, C₇-C₄₀ alkylarylidene and C₇-C₄₀arylalkylidene radicals; L is a divalent C₁-C₄₀ hydrocarbon radicaloptionally containing heteroatoms belonging to groups 13-17 of thePeriodic Table of the Elements or a divalent silylene radical containingup to 5 silicon atom; R¹ is linear or branched, saturated or unsaturatedC₁-C₂₀-alkyl radicals, optionally containing heteroatoms belonging togroups 13-17 of the Periodic Table of the Elements; R² is a linear orbranched, saturated or unsaturated C₁-C₂₀-alkyl radical, optionallycontaining heteroatoms belonging to groups 13-17 of the Periodic Tableof the Elements; R⁵ is a hydrogen atom or linear or branched, saturatedor unsaturated C₁-C₂₀-alkyl radical, optionally containing heteroatomsbelonging to groups 13-17 of the Periodic Table of the Elements; R¹⁴,equal to or different from each other, are hydrogen atoms or C₁-C₄₀hydrocarbon radicals optionally containing heteroatoms belonging togroups 13-17 of the Periodic Table of the Elements; and (b) an alumoxaneor a compound that forms an alkyl metallocene cation.
 2. The processaccording to claim 1 wherein the catalyst system further comprises c) anorgano aluminum compound.
 3. The process according to claim 1 wherein inthe compound of formula (V), M is titanium, zirconium or hafnium; X is ahydrogen atom, a halogen atom or a R group, wherein R has been definedas in claim 1; and L is a divalent bridging group selected from C₁-C₄₀alkylidene, C₃-C₄₀ cycloalkylidene, C₆-C₄₀ arylidene, C₇-C₄₀alkylarylidene, or C₇-C₄₀ arylalkylidene radicals optionally containingheteroatoms belonging to groups 13-17 of the Periodic Table of theElements, and silylene radical containing up to 5 silicon atoms.
 4. Theprocess according to claim 1 wherein in the compound of formula (V), Lis a group (Z(R″)₂)_(n) wherein Z is a carbon or a silicon atom, n is 1or 2 and R″ is a C₁-C₂₀ hydrocarbon radical optionally containingheteroatoms belonging to groups 13-17 of the Periodic Table of theElements.
 5. The process according to claim 1 wherein the polymerizationprocess is carried out using 1-hexene as a polymerization medium.